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b43: use 8K buffers for 64-bit DMA to workaround hardware bug

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Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Rafał Miłecki 2011-08-26 20:41:39 +02:00 committed by John W. Linville
parent 996bc370fa
commit 14a8083e67
2 changed files with 18 additions and 9 deletions
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24
drivers/net/wireless/b43/dma.c
View file

@ -419,26 +419,34 @@ static int alloc_ringmemory(struct b43_dmaring *ring)
gfp_t flags = GFP_KERNEL;
/* The specs call for 4K buffers for 30- and 32-bit DMA with 4K
* alignment and 8K buffers for 64-bit DMA with 8K alignment. Testing
* has shown that 4K is sufficient for the latter as long as the buffer
* does not cross an 8K boundary.
*
* alignment and 8K buffers for 64-bit DMA with 8K alignment.
* In practice we could use smaller buffers for the latter, but the
* alignment is really important because of the hardware bug. If bit
* 0x00001000 is used in DMA address, some hardware (like BCM4331)
* copies that bit into B43_DMA64_RXSTATUS and we get false values from
* B43_DMA64_RXSTATDPTR. Let's just use 8K buffers even if we don't use
* more than 256 slots for ring.
*/
u16 ring_mem_size = (ring->type == B43_DMA_64BIT) ?
B43_DMA64_RINGMEMSIZE : B43_DMA32_RINGMEMSIZE;
ring->descbase = dma_alloc_coherent(ring->dev->dev->dma_dev,
B43_DMA_RINGMEMSIZE,
&(ring->dmabase), flags);
ring_mem_size, &(ring->dmabase),
flags);
if (!ring->descbase) {
b43err(ring->dev->wl, "DMA ringmemory allocation failed\n");
return -ENOMEM;
}
memset(ring->descbase, 0, B43_DMA_RINGMEMSIZE);
memset(ring->descbase, 0, ring_mem_size);
return 0;
}
static void free_ringmemory(struct b43_dmaring *ring)
{
dma_free_coherent(ring->dev->dev->dma_dev, B43_DMA_RINGMEMSIZE,
u16 ring_mem_size = (ring->type == B43_DMA_64BIT) ?
B43_DMA64_RINGMEMSIZE : B43_DMA32_RINGMEMSIZE;
dma_free_coherent(ring->dev->dev->dma_dev, ring_mem_size,
ring->descbase, ring->dmabase);
}

3
drivers/net/wireless/b43/dma.h
View file

@ -161,7 +161,8 @@ struct b43_dmadesc_generic {
} __packed;
/* Misc DMA constants */
#define B43_DMA_RINGMEMSIZE PAGE_SIZE
#define B43_DMA32_RINGMEMSIZE 4096
#define B43_DMA64_RINGMEMSIZE 8192
/* Offset of frame with actual data */
#define B43_DMA0_RX_FW598_FO 38
#define B43_DMA0_RX_FW351_FO 30